Prescribers and patients need a proper surveillance system for cognitive side effects

A growing number of observational studies have shown the critical role of potentially inappropriate medications for increasing the risk of cognitive impairment. In a linked paper, Billioti de Gage and colleagues (doi:10.1136/bmj.g5205) extend the pharmacoepidemiological research on the adverse cognitive effects of benzodiazepines with an investigation of their link with Alzheimer’s disease.1 Their results suggest that long term exposure to benzodiazepines might be a modifiable risk factor for this condition.

The authors conducted a nested case-control study of about 2000 older members of a public drug plan in the province of Quebec, Canada. They observed a cumulative dose-effect association between exposure to benzodiazepines (at least 90 days) and risk of developing Alzheimer’s disease and found that exposure lasting more than 180 days was associated with a nearly twofold increase in risk. In further analyses, they showed that longer acting benzodiazepines were associated with greater risk of developing Alzheimer’s disease compared with shorter acting benzodiazepines, adding support for a causal association.